Modern steel mills are required to produce a finished product which must meet critical size requirements within a very small tolerance. Most rod mills are capable of producing a finished product within a given tolerance range until the steel work product wears the contours of the forming rolls so that the finished product has a shape which is not acceptable to a customer. To correct minor irregularities in shape, the steel mill industry has, at times, employed a process known as peeling, wherein a finished rod is pulled through a die to remove portions of the surface of the rod to restore the shape of the finished product to one that is now acceptable to a customer and the surface is now true and free of imperfections. The peeling process is capable of correcting for only small deviations in the gauge of the finished product.
This invention provides a rolling assembly in which at least three and preferably four equally spaced rollers are mounted in a housing about an axis through which a steel rod or wire passes. The rollers are mounted in a robust assembly which can exert substantial pressure on the rollers to change the shape of the work to compensate for minor shape deviations in the shape of the work product caused by wear of the rollers in the reducing mill. The assembly is provided with a roller positioning device which moves the rollers in the roller assembly in concert toward and away from the axis of the work piece passing between the rollers.
At the same time, the roller assembly in which the rollers are mounted is pivotable through a predetermined angle (say 45xc2x0) to change the orientation of the entire roller assembly with respect to the workpiece passing therethrough. In this instance, premature wear of the roller surfaces of the rollers of the sizing guide is minimized because the rollers of the sizing guide are constantly changing position with respect to the surface of the work product.
The cross sectional shape of a work product exiting from a finishing stand of a multi stand steel mill is dependent upon the accuracy of the profile existing in the rollers of the mill stand. When the rollers of the mill have worn to the extent that the work product has a gauge or shape which lies outside the acceptable tolerance range and no further corrective actions involving roller adjustment are capable of restoring the work product to an acceptable gauge, the rollers in the mill must be replaced because the surface contours of the reducing rollers have undergone wear and abrasion by the constant passage of the work product between the reducing rolls.
Some wear patterns in the rollers are predictable, depending on the rolling process to which the mill stand rollers are subjected and most operators of modern steel mills instinctively known that shape distortion of the finished product will inevitably result. At times, the distortion in work product shape may be corrected by further processing the work product to remove such distortion after passage through the final mill stand (if the distortion is not too great). The worn rolls in the mill may then continue to be used to produce a useful work product beyond the usual wear period due to the correction applied to the work product. In the past this correction has usually been accomplished by xe2x80x9cpeelingxe2x80x9d some metal from the surface of the malshaped workpiece using a die such that small shape deformations may be removed by this process.
The sizing roll stand of this invention is capable of restoring the exterior shape of a malformed work product exiting from a steel mill to an acceptable size and shape. The apparatus of this invention is capable of providing corrections for the same shape distortions as the xe2x80x9cpeelingxe2x80x9d process to which reference has been made, but at a very high speed. The rollers of the sizing roll stand may or may not be externally driven.